Stability Analysis Of Surrounding Rock In Moweishan Yunnel

Along with our country social economic increasing, traffic infrastructure constructions will flourish. The development of transport, especially in the Midwest and other mountainous regions, inevitably accompanied by the emergence of a large number of tunnel engineering. At present, separated tunnel, multi arch tunnel and tunnel with small interval is the more common form of tunnel in the construction of tunnel engineering. Building railway, highway, tunnel engineering in the mountainous, hilly landform and geological conditions complex areas will encounter a lot of problems. These tunnels due to topography, traffic design requirements and other restrictions, often have to compress the distance between two holes, build as the tunnel arch or tunnel with small interval form. The tunnel with small interval with high safety, low cost, long term reliability is guaranteed and the construction process usual as the common separated tunnel. Because of these advantages, tunnel with small interval is paid more and more attention, has become one of the main forms of special geological and topographical conditions of mountain tunnel project, it also developed a number of specific for small spacing tunnel construction.In this paper based on the tunnel of the Moweishan, according to the characteristics of complex engineering geological conditions with grade V surrounding rock, shallow with small distance. Analysis of the tunnel surrounding rock stress distribution, deformation characteristics and the interval of the tunnel construction face, discussed on the stability of surrounding rock and construction process control in the V class surrounding rock of small spacing tunnel. Through the simulation analysis we found:by using the method of CRD in the excavation of the upper part surrounding rock form stress concentration zone in the arch waist and arch foot, with the excavation of the lower part,the stress concentration zone move to the arch of the foot and the maximum stress value increased further. Small interval tunnel two tunnel interactions in the excavation process, especially the rock between two holes affected most strongly linked to the formation of stress concentration region. For strain due to excavation of folder makes the vertical displacement of surrounding rock is further increased. For the different tunnel excavation space, through the analysis found that the construction small interval tunnel excavation distance can’t be too small, because too small displacement of surrounding rock and the stress value will be affected, the stress and displacement variation of each construction step are significantly increased, it is extremely unfavorable to the stability of tunnel, when the excavation disturbance of surrounding rock caused by exceeding the limits of endurance, the tunnel is likely to damage or even instability; With the increasing of tunnel construction space, is not conducive to control the construction time. Therefore, control of construction of small spacing tunnel spacing the first and folder hole is very important. tunnel project reasonable space should be determined by the calculation results of different face construction space and time requirements. The research in this paper, which has a certain practical significance to the future similar project construction.